1. Technical Field of the Invention
The present invention relates to the interconnection of wireless office environments with a public cellular telephone network, and more particularly, to a network hub providing for transmission of messages from the hub to the public cellular telephone network using the SS7 protocol and the transmission of messages from the hub to the wireless office environment using the TCP/IP protocol.
2. Description of Related Art
Public access cellular telephone systems are currently available for use throughout the world. As a result of the success of such systems in providing mobile telecommunication services to the public, considerable interest has arisen in the corporate sector to provide a wireless communication feature add on to conventional private wireline telephone systems. Such a feature is typically implemented through the use of a private cellular telephone system.
Due to the costs of mobile terminals, it is preferable in any private cellular telephone system established by a business to utilize the same type of mobile terminals as are used within public access cellular telephone systems. Furthermore, because many employees already own mobile terminals and have subscriptions with a public access telephone system, it is preferable that the utilized mobile stations be capable of operating with and between each of the systems. At a minimum, this requires that the private cellular telephone system operate within the same cellular frequency band as the public access cellular telephone system, and use the same type or compatible switching equipment and base stations. It is also likely that the radio frequency coverage regions of the private cellular telephone system and the public access cellular telephone system may at least partially overlap. Furthermore, the private cellular telephone system and the public access cellular telephone system must communicate with each other regarding the servicing of mobile stations, the allocation of channels (frequencies) for communication, the routing of communications, and the handing off of mobile station communications.
It is preferred that the wireless offices be connected to an existing home location register (HLR) of the cellular network to enable automatic roaming between the cellular network and the wireless office. As the popularity of wireless offices increases, each new wireless offices must be connected to the signaling system no. 7 (SS7) network that forms the backbone of existing public access cellular telephone systems. Each additional connection of a wireless office adds an additional node to the cellular network and requires a great deal of work to update each node within the cellular network with knowledge of a new wireless office node. This work level is repeated by each wireless office that is added to the network creating a huge task for the cellular network provider.
Furthermore, when a private network is added as a node to the public access cellular telephone system, the wireless office nodes will not be owned by the cellular network providers. This raises several security concerns, and cellular network operators are not keen on adding nodes that are not under their total control. Nodes not controlled by the cellular network provider raise a serious security risk due to unscrupulous third parties access to the private nodes. Additionally, nodes not under the control of the cellular network operators may often be restarted which raises the number of management messages which must be transmitted by the network. Thus, a great many problems and concerns arise in the direct connection of a number of new wireless office nodes directly to a public access cellular network.
The present invention overcomes the foregoing and other problems with an improved communications system utilizing a network hub. A first public access cellular telephone network operates according to the signaling system no. 7 (SS7) protocol for transmitting signals between various nodes and the public access network. A second communications system comprises a TCP/IP network utilizing the TCP/IP protocol. The second network is interconnected with a plurality of private wireless networks and transmits signals via the TCP/IP protocol.
A network hub interconnects the first and second communications networks and enables the transfer of signals therebetween. The network includes processing means for converting signals from being carried by the SS7 protocol to the TCP/IP protocol and vice versa. This is accomplished by replacing the MTP and SSCP layers of an SS7 protocol signal with a TCP/IP layer for transmissions from the SS7 network to the TCP/IP network, and for replacing a TCP/IP layer with MTP and SSCP layers for transmissions from the TCP/IP network to the SS7 network.
A translation table within the network hub enables the location of mobile stations being served by wireless networks connected to the network hub to be determined. The translation table includes the mobile identification numbers of registered mobile stations. Each mobile identification number entry further includes an associated IP address for the wireless network serving the mobile station. This enables calls from the public network to be directed to the wireless office serving a mobile station. A North American Cellular Network address table provides the signaling control points (addresses) for all nodes within the public access cellular telephone network. This enables transmissions from the wireless networks to be directed to any location within the public access cellular telephone network once the communication reaches the network hub.